Tires began as a durable material circling a fragile wheel, such as a steel tire on a spoked wooden wagon wheel. I So when inventors first came up with better tires, they didn’t quickly think of the pneumatic rubber kind we know today Long after air-filled versions became common, they were seen more as an outer layer than as an independent structure.
Vulcanization, discovered in 1839 by Charles Goodyear, made rubber durable enough for tires for the first time. But the earliest air-filled tires didn’t put the rubber on the outside. They were buggy tires invented by Robert William Thomson, a Scottish engineer who in 1845 patented a riveted leather wrap bolted to the wheel rims, supported I by an inflated rubber-coated canvas inner tube. Thomson continued to patent key pneumatic-tire concepts up to his death in 1873. Not until the 1888 patent issued to John’s Boyd Dunlop, a British veterinary surgeon, however, did inflated rubber tires come into their own, at first for bicycles and tricycles (including that of Dunlop’s nine-year-old son, whose bumpy rides had inspired the invention).
Carriages and wagons also used pneumatic tires, and when automobiles came along, the first ones fitted to them were so-called clincher tires. These had “beads,” or inner rims, made of rubber and formed with a barb to let a mechanical fastener hold them on. Soon after, other inventors brought forward the idea of using a wire cable to form the bead of the tire, with that bead nesting inside a flange on the outer rim of the wheel—the so-calledf straight-sided tire. At about the same time, tire treads began thickening and being patterned for better traction.
In the 1930s, new, synthetic materials such as rayon replaced cotton in the tires’ plies, greatly improving the strength of their cord reinforcement. Synthetic rubber for increased durability emerged in Germany in the late 1930s. Then tubeless tires, a wartime project of B. E Goodrich for which a patent was granted in 1952, melded all of the pneumatic tire’s features into the single, durable unit today’s drivers are familiar with.
By the time radiais hit North America, tires were already very complex structures, although their behavior was only beginning to be truly understood through laboratory testing and mathematical modeling.
—T.M.
